This invention relates to thermal aging of catalytic converters for engine emission control qualification testing and, more particularly, to methods and apparatus for carrying out thermal aging processes.
The qualification of exhaust emission equipment for use with automotive vehicle engines requires testing of its operation under prescribed conditions when new and at various subsequent intervals of normal use in order to meet various federal and international emission control regulations. Thus, exhaust gas catalytic converters intended for automotive engine exhaust emission control are tested with their intended or comparable engines at various actual or simulated mileage intervals to their required maximum life.
To provide the catalytic converters needed for testing at the various vehicle mileage conditions, catalytic converters are thermally aged by operation of one or more converter units connected to the exhaust system of an engine under operating conditions of air/fuel ratio, temperature and mass flow representing the thermal degradation/ deterioration of the catalyst over a prescribed corresponding vehicle operating mileage. This is done in an aging facility using a large number of engines, each connected with one or several catalytic converters. In view of the number of engines required and their cost, a more cost effective and efficient apparatus for aging catalytic converters is desired.
The present invention provides methods and apparatus for the thermal aging of catalytic converters which uses a relatively simple gas dynamic exhaust gas generator in place of a complex piston engine for generating the heated exhaust gas needed for the thermal aging of catalytic converters. The gas generator includes a gas dynamic air compressor, an exhaust gas turbine connected for driving the compressor and a combustor or burner connected to receive compressed air from the compressor, to burn fuel in the compressed air to form heated combustion products, and to deliver the combustion products as heated compressed exhaust gas to the turbine for driving the compressor.
A control is provided to control the ratio of air and fuel in the combustor and an exhaust conduit from the turbine provides for connection with one or more catalytic converters to be aged. Supplemental air and fuel delivery apparatus may also be connected with the exhaust conduit for supplying added air and fuel to control the operating cycle conditions as desired in the catalytic converter or converters. A manifold may be connected with the exhaust conduit for distributing the exhaust gas to several catalytic converters for aging a plurality of converters with one exhaust gas generator.
In a preferred embodiment, the cost of the converter aging apparatus is reduced by using a commercially available engine exhaust turbocharger to provide the needed compressor and turbine. A suitable combustor is connected between the compressor and turbine and the desired fuel and air connections and controls and an exhaust conduit are provided to complete the apparatus. The turbocharger may be sized and controlled to provide the exhaust gas conditions needed for aging of one or a plurality of catalytic converters at the same time.
These and other features and advantages of the invention will be more fully understood from the following detailed description of the invention taken together with the accompanying drawings.